I think most of what people have written here is correct, but if your plane is nose heavy you should correct that. A nose heavy plane requires a higher angle of attack to maintain level flight, so moving the CG back will reduce the angle at which your plane flies. That will reduce drag, because the bottom of the fuselage will not be creating as much drag, and the wing will have less drag. You might find the elevator a little more sensitive, but as long as you stick with the recommended CG it should be fine. You might want some expo, or slightly reduced throws, or you might just like it.

Also, I agree that an OS 25 LA is a little marginal for a 4 1/2 lb airplane, especially with a 9x6 prop. I would try a 10x4, or maybe a 10x3 if you can find one. Perhaps the best would be a 10x4 cut down to 9 1/2 and re-balanced. None of this affects the angle of flight, but it should give you more low speed thrust, which can help you out in a pinch, and reduce your take-off distance.

Jim